In Japanese Patent Laid-Open Nos. 2009-118607 and 2009-118608, a conventional battery charging apparatus 300 incorporating a short-circuit regulator/rectifier is described (FIG. 3).
The conventional battery charging apparatus 300 includes a first generator terminal “TG1” to which a first output “Ga” of an alternating-current generator “G” is connected, and a second generator terminal “TG2” to which a second output “Gb” of the alternating-current generator “G” is connected. The battery charging apparatus 300 further includes a first battery terminal “TB1” to which a positive electrode side of a battery “B” is connected, and a second battery terminal “TB2” to which a negative electrode side of the battery “B” is connected, the battery “B” and a fuse “F” being connected in series with each other between the first battery terminal “TB1” and the second battery terminal “TB2”.
The battery charging apparatus 300 further includes a rectifying circuit 300A that has four diodes “A1” to “A4” and two thyristors “SCR1” and “SCR2”, rectifies an output current of the alternating-current generator “G” and outputs the rectified current to the first battery terminal “TB1”.
The battery charging apparatus 300 further includes a controlling circuit “CON” that controls the thyristors “SCR1” and “SCR2” of the rectifying circuit “300A” to rectify the output current of the alternating-current generator “G”.
With the conventional battery charging apparatus 300, when the battery “B” is reversely connected, a current “I” from the battery “B” flows to the fuse “F” through the rectifier (the diodes “A1” to “A4”).
The current “I” makes the fuse “F” blow. As a result, application of a reverse voltage to an electronic device “D” is prevented.
On the other hand, there is a conventional battery charging apparatus 400 incorporating an open-circuit regulator/rectifier, for example (FIG. 4).
As with the battery charging apparatus 300 described above, the conventional battery charging apparatus 400 includes a first generator terminal “TG1”, a second generator terminal “TG2”, a first battery terminal “TB1” and a second battery terminal “TB2”. The battery charging apparatus 400 further includes a rectifying circuit 400A that has two diodes “E1” and “E2” and two thyristors “SCR1” and “SCR2”, rectifies an output current of an alternating-current generator “G” and outputs the rectified current to the first battery terminal “TB1”. The battery charging apparatus 400 further includes a controlling circuit “CON” that controls the thyristors “SCR1” and “SCR2” of the rectifying circuit 400A to rectify the output current of the alternating-current generator “G”.
In the battery charging apparatus 400, the rectifier part is formed by the thyristors “SCR1” and “SCR2”. In a normal operation in which the output current of the alternating-current generator “G” is rectified, the thyristors “SCR1” and “SCR2” are turned on and off under the control of the controlling circuit “CON”.
However, when the alternating-current generator “G” does not output a current (that is, does not revolve), the controlling circuit “CON” does not control the thyristors “SCR1” and “SCR2”, and the thyristors “SCR1” and “SCR2” do not operate (that is, are in the off state) even if the battery “B” is reversely connected. In this case, when the battery “B” is reversely connected, there is no path through which a current “I” can flow to a fuse “F” (FIG. 4).
In other words, when the battery “B” is reversely connected, the fuse “F” does not blow. Therefore, a reverse voltage is applied to an electronic device “D”.
Another conventional battery charging apparatus 500 incorporating an open-circuit regulator/rectifier differs from the conventional battery charging apparatus 400 described above in that it further includes an additional diode “da” that is connected to the first battery terminal “TB1” at a cathode thereof and to the second battery terminal “TB2” at an anode thereof (FIG. 5).
When the battery “B” is reversely connected, the additional diode “da” provides a path through which a current “I” can flow to a fuse “F”.
The current “I” makes the fuse “F” blow. As a result, application of a reverse voltage to an electronic device “D” is prevented.
However, in the conventional battery charging apparatus 500 incorporating the open-circuit regulator/rectifier shown in FIG. 5 described above, the additional diode “da” has to have a current carrying capacity enough to withstand a current that makes the fuse “F” blow even though the diode is not used in the normal operation.
Thus, the additional diode “da” poses a problem that the manufacturing cost of the battery charging apparatus 500 increases.
A battery charging apparatus, according to an embodiment of an aspect of the present invention, being the battery charging apparatus that controls charging of a battery by an alternating-current generator, and the battery charging apparatus comprising:
a first generator terminal to which a first output of the alternating-current generator is connected;
a second generator terminal to which a second output of the alternating-current generator is connected;
a first battery terminal to which a positive electrode side of the battery is connected in a normal connection condition of the battery;
a second battery terminal to which a negative electrode side of the battery is connected in the normal connection condition of the battery, the battery and a fuse being connected in series with each other between the first battery terminal and the second battery terminal;
a rectifying circuit that has a first switch element connected to the first battery terminal at a first end thereof and to the first generator terminal at a second end thereof, a second switch element connected to the first battery terminal at a first end thereof and to the second generator terminal at a second end thereof, a first rectifying element connected to the first generator terminal at a first end thereof and to the second battery terminal at a second end thereof, and a second rectifying element connected to the second generator terminal at a first end thereof and to the second battery terminal at a second end thereof, rectifies an output current of the alternating-current generator and outputs the rectified current to the first battery terminal;
a detecting circuit that detects a reverse connection condition of the battery in which the negative electrode side of the battery is connected to the first battery terminal and the positive electrode side of the battery is connected to the second battery terminal, and controls either of the first switch element and the second switch element based on a result of the detection; and
a controlling circuit that controls the first switch element and the second switch element of the rectifying circuit to rectify the output current of the alternating-current generator,
wherein in a case where the controlling circuit stops controlling the first switch element and the second switch element, and the first switch element and the second switch element are turned off,
the detecting circuit forcedly turns on at least one of the first switch element and the second switch element when the detecting circuit detects the reverse connection condition of the battery.
In the battery charging apparatus,
the detecting circuit detects the reverse connection condition of the battery by detecting that a polarity of a voltage at the first battery terminal or the second battery terminal is different from the polarity in the normal connection condition.
In the battery charging apparatus,
the detecting circuit detects the reverse connection condition of the battery by detecting that a magnitude of the voltage at the first battery terminal or the second battery terminal is equal to or greater than a preset threshold.
In the battery charging apparatus,
in the case where the controlling circuit stops controlling the first switch element and the second switch element, and the first switch element and the second switch element are turned off,
when the detecting circuit detects the reverse connection condition of the battery, the detecting circuit forcedly turns on either of the first switch element and the second switch element, thereby causing a current to flow to the fuse connected between the first battery terminal and the second battery terminal to make the fuse blow.
In the battery charging apparatus,
the first switch element is a first thyristor connected to the first battery terminal at a cathode thereof and to the first generator terminal at an anode thereof,
the second switch element is a second thyristor connected to the first battery terminal at a cathode thereof and to the second generator terminal at an anode thereof,
the first rectifying element is a first rectifying diode connected to the first generator terminal at a cathode thereof and to the second battery terminal at an anode thereof, and
the second rectifying element is a second rectifying diode connected to the second generator terminal at a cathode thereof and to the second battery terminal at an anode thereof.
In the battery charging apparatus,
the detecting circuit has:
a Zener diode connected to the second battery terminal at a cathode thereof;
a first detecting diode connected to a gate of the first thyristor at a cathode thereof and to an anode of the Zener diode at an anode thereof; and
a second detecting diode connected to a gate of the second thyristor at a cathode thereof and to the anode of the Zener diode at an anode thereof.
In the battery charging apparatus,
the detecting circuit further has:
a first detecting resistor connected between the gate of the first thyristor and the cathode of the first detecting diode; and
a second detecting resistor connected between the gate of the second thyristor and the cathode of the second detecting diode.
In the battery charging apparatus,
an electronic device is connected in parallel with the fuse between the first battery terminal and the second battery terminal.
In the battery charging apparatus,
in the case where the controlling circuit stops controlling the first switch element and the second switch element, and the first switch element and the second switch element are turned off,
the detecting circuit forcedly turns on both the first switch element and the second switch element when the detecting circuit detects the reverse connection condition of the battery.
In the battery charging apparatus,
the detecting circuit is driven by a current supplied from the battery reversely connected.
In the battery charging apparatus,
the controlling circuit stops controlling the first switch element and the second switch element in a case where the alternating-current generator stops revolving and does not provide the output current.
In the battery charging apparatus,
the controlling circuit is driven by at least the output current provided by the alternating-current generator.
In the battery charging apparatus,
in the normal connection condition of the battery, the detecting circuit does not control the first switch element and the second switch element.
A method of controlling a battery charging apparatus, the battery charging apparatus comprising: a first generator terminal to which a first output of the alternating-current generator is connected; a second generator terminal to which a second output of the alternating-current generator is connected; a first battery terminal to which a positive electrode side of the battery is connected in a normal connection condition of the battery; a second battery terminal to which a negative electrode side of the battery is connected in the normal connection condition of the battery, the battery and a fuse being connected in series with each other between the first battery terminal and the second battery terminal; a rectifying circuit that has a first switch element connected to the first battery terminal at a first end thereof and to the first generator terminal at a second end thereof, a second switch element connected to the first battery terminal at a first end thereof and to the second generator terminal at a second end thereof, a first rectifying element connected to the first generator terminal at a first end thereof and to the second battery terminal at a second end thereof, and a second rectifying element connected to the second generator terminal at a first end thereof and to the second battery terminal at a second end thereof, rectifies an output current of the alternating-current generator and outputs the rectified current to the first battery terminal; a detecting circuit that detects a reverse connection condition of the battery in which the negative electrode side of the battery is connected to the first battery terminal and the positive electrode side of the battery is connected to the second battery terminal, and controls either of the first switch element and the second switch element based on a result of the detection; and a controlling circuit that controls the first switch element and the second switch element of the rectifying circuit to rectify the output current of the alternating-current generator,
wherein in a case where the controlling circuit stops controlling the first switch element and the second switch element, and the first switch element and the second switch element are turned off,
the detecting circuit forcedly turns on at least one of the first switch element and the second switch element when the detecting circuit detects the reverse connection condition of the battery.
A battery charging apparatus according to an aspect of the present invention includes a detecting circuit that detects a reverse connection condition of a battery in which a negative electrode side of the battery is connected to a first battery terminal and a positive electrode side of the battery is connected to a second battery terminal, and controls either of a first switch element and a second switch element based on a result of the detection.
And in a case where a controlling circuit stops controlling the first switch element and the second switch element, and the first switch element and the second switch element are turned off, the detecting circuit forcedly turns on at least one of the first switch element and the second switch element when the detecting circuit detects the reverse connection condition of the battery.
In this way, when the battery is reversely connected, a path through which a current can flow to a fuse “F” is provided. The current makes the fuse blow. As a result, application of a reverse voltage to an electronic device is prevented.
Furthermore, any additional diode or the like is not required to provide a path through which a current can flow to the fuse F when the battery is reversely connected. Therefore, the manufacturing cost of the battery charging apparatus can be reduced.